Merge branch 'master' into jgrpp

# Conflicts:
#	.gitignore
#	CMakeLists.txt
#	src/3rdparty/optional/optional.hpp
#	src/group_cmd.cpp
#	src/industry_cmd.cpp
#	src/misc_gui.cpp
#	src/video/sdl2_v.cpp

src/saveload/afterload.cpp

@@ -3293,8 +3293,7 @@ bool AfterLoadGame()
 					cur_skip = prev_tile_skip;
 				}
 
-				/*C++17: uint &this_skip = */ skip_frames.push_back(prev_tile_skip);
-				uint &this_skip = skip_frames.back();
+				uint &this_skip = skip_frames.emplace_back(prev_tile_skip);
 
 				/* The following 3 curves now take longer than before */
 				switch (u->state) {

src/saveload/engine_sl.cpp

@@ -191,8 +191,7 @@ static void Load_EIDS()
 	_engine_mngr.clear();
 
 	while (SlIterateArray() != -1) {
-		/*C++17: EngineIDMapping *eid = &*/ _engine_mngr.emplace_back();
-		EngineIDMapping *eid = &_engine_mngr.back();
+		EngineIDMapping *eid = &_engine_mngr.emplace_back();
 		SlObject(eid, _engine_id_mapping_desc);
 	}
 }

src/saveload/saveload.cpp

@@ -46,6 +46,9 @@
 #include "../scope.h"
 #include <atomic>
 #include <string>
+#ifdef __EMSCRIPTEN__
+#	include <emscripten.h>
+#endif
 
 #include "../tbtr_template_vehicle.h"
 
@@ -2928,6 +2931,10 @@ static void SaveFileDone()
 
 	InvalidateWindowData(WC_STATUS_BAR, 0, SBI_SAVELOAD_FINISH);
 	_sl.saveinprogress = false;
+
+#ifdef __EMSCRIPTEN__
+	EM_ASM(if (window["openttd_syncfs"]) openttd_syncfs());
+#endif
 }
 
 /** Set the error message from outside of the actual loading/saving of the game (AfterLoadGame and friends) */

src/saveload/waypoint_sl.cpp

@@ -192,8 +192,7 @@ static void Load_WAYP()
 	int index;
 
 	while ((index = SlIterateArray()) != -1) {
-		/*C++17: OldWaypoint *wp = &*/ _old_waypoints.emplace_back();
-		OldWaypoint *wp = &_old_waypoints.back();
+		OldWaypoint *wp = &_old_waypoints.emplace_back();
 
 		wp->index = index;
 		SlObject(wp, _old_waypoint_desc);